It has been a challenging few weeks for architect Thomas Heatherwick, whose proposals for elevated green urban spaces in both London and New York City face uncertain futures. While the specifics vary, there may be lessons for elevated parks that spans both cases — and if these fail to move forward, it could spell the end of a decade-long trend for lofted public parks.

The Garden Bridge project in London has long been criticized based on its cost and officials are getting serious about making sure the investment (especially tax dollars) will pay off. The design has been touted as a kind of High Line Park for England’s capital, but unlike the High Line it is a brand new construction project (not adaptive reuse) and not positioned to revitalize areas of its city.

At the heart of the issue, unsurprisingly, is money: an initial projection of £60,000,000 has blossomed into an estimated cost of around £200,000,000. Shockingly, even cancelling the project now would result in a bill of over £40,000,000, despite the fact that construction has not even started. While £70,000,000 in private funding was secured at the outset, the rest would have to be covered by taxpayer money, which is less than popular with the public. As of now, the mayor’s financial inquiry has resulted in a recommendation to scrap the project.

According to a governmental report on the project, “Decisions on the Garden Bridge were driven by electoral cycles rather than value for money,. From its inception when there was confusion as to its purpose, through a weak business case that was constructed after contracts had been let and money had been spent, little regard has been had to value for money.” It is unclear whether the project is stalled or slated for abandonment, but it looks unlikely to proceed at this point.

Meanwhile, across the pond, Heatherwick’s proposed Pier 55 project (images by Luxigon), an elevated park stretching out over the water next to Manhattan, is also stalled out, at least for now. Its permit was recently revoked in part based on environmental studies that concluded it would disrupt local marine habitats. There are also concerns that it will block views along the waterfront.

The 10,000-square-foot, $200,000,000 park was designed to replace a disused pier in the heart of New York City, but once again it lacks some of the conditions that made the High Line a viable solution, particularly its lack of reuse. Perhaps the elevated parks trend is coming to an end, or (more likely): it is too often pitched as a solution, even in cases where there is no obvious problem to be solved.